All liquids contain more or less air in free, dispersed or dissolved form. Within the industry which employs process water, there is often a need to remove this air. Above all within the food industry, this is often necessary, since a content of air may result in the deterioration of the quality of the product, or alternatively hamper those processes that are being employed.
For example, in the production of fruit juices or beverages containing fruit juices, it is particularly important, since oxygen oxidizes the product and destroys the important vitamin C. Too large a content of air is also a disadvantage as regards the production of carbonated drinks, since it makes it more difficult to add carbon dioxide. Milk-based products are also deaerated, since a large content of air results in a deterioration in quality and disrupts the process in that scorching of the product, so-called fouling in heat treatment plants increases with an increased air content. An excessively large air content may also cause frothing in certain processes, which is difficult to handle.
There are a number of methods and apparatuses employed in the art for removing air from liquids. A common method entails that the liquid, at a certain temperature, is distributed in a vacuum vessel. The pressure in the vessel is kept at such a level that a certain degree of boiling occurs, so-called flash. The alternative to flash is that the vacuum vessel is filled with a packing material through which the liquid is caused to pass, but without the occurrence of boiling. This method may be speeded up by introducing, under partial vacuum, a gas such as carbon dioxide into the liquid, and by such means drive out and replace the air with the gas. This method is often entitled stripping and is particularly suitable for liquids which are later to be carbonated.
The methods in existence today often function satisfactorily but entail that there is a need to invest in special equipment. In certain cases, such equipment may also be extremely bulky.